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DroidLogic SubTitleService EUVDEUVD-2026-115548

| CVE-2026-119739 MEDIUM
Out-of-bounds Write (CWE-787)
2026-11-02 VulnCheck GHSA-mw5f-6hxf-hxw4
6.9
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach unauthenticated tcp/10100 socket or deliver malicious .sub
  2. Delivery
    Send crafted SET_CONTR with oversized alpha
  3. Exploit
    Drive change_data index past 4-element PixelDatas array
  4. Execution
    Out-of-bounds write zeros adjacent stack bytes
  5. Impact
    Crash or silently corrupt SubTitleService

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires that the Amlogic DroidLogic SubTitleService be reachable, either via its unauthenticated tcp/10100 control socket on the local network or by getting the device to parse an attacker-supplied VobSub .sub file. The concrete trigger is a SET_CONTR command whose attacker-controlled alpha value drives the change_data index beyond the fixed four-element PixelDatas array in vob_fill_pixel(). No authentication and no user interaction are required (PR:N/UI:N). Limiting factors: the tcp/10100 service is typically LAN-exposed rather than internet-facing by default, so an attacker generally needs local/adjacent network position or a delivery path for the malicious subtitle file; and the memory effect is confined to zeroing adjacent stack bytes, which limits realistic impact to silent corruption or a service crash rather than reliable control of execution.

Impact

This is a medium-severity, lower-real-risk issue despite being remotely triggerable. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms network-reachable, low-complexity, unauthenticated triggering with no user interaction - consistent with the description's unauthenticated tcp/10100 socket. Crucially, impact is constrained to availability only (VC:N/VI:N/VA:L): the out-of-bounds write (CWE-787) zeros adjacent stack bytes, producing silent corruption or a process crash rather than demonstrated code execution or data disclosure, so the practical outcome is a denial of service of the SubTitleService. The vuln.today decision label is 'this_month' (not act_now/emergency), aligning with the moderate 6.9 score. A public PoC reference exists but is not verified as working exploit code, and there is no CISA KEV listing - so this is not confirmed active exploitation. EPSS is not provided in the input, so exploitation probability cannot be weighed; this absence should be noted rather than assumed low. Net: easy to trigger but limited blast radius on a niche consumer device, making this a routine-patch priority rather than an emergency.

Exploit ScenarioDerived

An attacker with network access to an exposed Nexbox A95X box connects to the unauthenticated tcp/10100 socket (or gets the device to parse a malicious .sub file) and sends a crafted SET_CONTR command carrying an oversized alpha value. The alpha drives the change_data index past the fixed four-element PixelDatas array in vob_fill_pixel(), zeroing adjacent stack bytes and crashing or silently corrupting the SubTitleService. A public PoC reference (a disclosure blog) exists but is not verified as working exploit code.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Nov 02, 2026

An out-of-bounds stack write in the VobSub subtitle decoder (libsub_vob) of the Amlogic DroidLogic SubTitleService allows remote attackers to corrupt memory on Nexbox A95X (Amlogic S905X) TV boxes and other devices built from the Amlogic Android SDK. A crafted SET_CONTR command carrying an attacker-controlled alpha value drives the change_data index past the end of the fixed four-element PixelDatas array inside vob_fill_pixel(), zeroing adjacent stack bytes; the payload can arrive over the unauthenticated tcp/10100 socket or by getting the device to parse a malicious .sub file. No authentication and no user interaction are required, but the assessed impact is limited to silent stack corruption or a process crash rather than code execution, and the tcp/10100 service is typically LAN-exposed rather than internet-facing. A public PoC reference exists; it is not verified as working exploit code, and no confirmed active exploitation has been reported.

RemediationAI

No vendor-released patch identified at time of analysis, so treat mitigation as configuration control until Amlogic or the device OEM publishes fixed firmware; track the VulnCheck advisory (https://www.vulncheck.com/advisories/amlogic-droidlogic-subtitleservice-out-of-bounds-write-via-vobsub-set-contr) and the researcher write-up (https://mstreet97.github.io/security-research/vulnerability-disclosure/embedded/cve/2026/10/29/From-UART-to-root-android-version.html) for a fix. The practical containment is to remove reachability to the unauthenticated tcp/10100 SubTitleService socket: segment the TV boxes onto an isolated or untrusted VLAN, block tcp/10100 at the LAN boundary and between guest and trusted networks, and avoid port-forwarding it, accepting that any LAN peer that can still reach the port retains the ability to trigger the crash. In addition, avoid opening or auto-loading VobSub .sub files from untrusted sources on these devices, since parsing such a file is the alternate path into vob_fill_pixel(); this costs compatibility with sideloaded external subtitles but removes the file-delivery vector. Where the subtitle service is not needed at all, disabling it (or the application that hosts it) eliminates both paths at the cost of losing subtitle rendering on that box.

Affected VersionsENISA

A95X NEXBOX-A95X-AP6330
Amlogic Android SDK 0

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Technical ContextAI · show details

The affected component is libsub_vob, the VobSub (.sub/.idx) subtitle parsing library inside Amlogic's DroidLogic SubTitleService, which ships in the Amlogic Android SDK and on consumer TV boxes such as the Nexbox A95X (Amlogic S905X). The flaw is a classic CWE-787 out-of-bounds write: vob_fill_pixel() indexes a fixed, four-element PixelDatas array on the stack using the change_data value, which is derived from the alpha field of a SET_CONTR command and is not bounds-checked. Because the write pattern is a zeroing operation, an out-of-range index overwrites adjacent stack bytes with zero rather than attacker-chosen data, which explains the assessed integrity and confidentiality impact of none and the low availability impact. Input reaches the parser through two paths: the SubTitleService control socket on tcp/10100, which performs no authentication, and local parsing of an attacker-supplied VobSub .sub file. The trigger requires no privileges (PR:N) and no user interaction (UI:N) once the service is reachable, but the network listener is normally confined to the LAN, so a remote attacker generally needs adjacent/local network position or a separate file-delivery vector.

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Severity by source

Vendor (VulnCheck) PRIMARY 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
vuln.today AI 5.3 MEDIUM

Unauthenticated, low-complexity trigger over a network socket (AV:N/AC:L/PR:N/UI:N); the write only zeros bytes causing a crash, so no C/I impact and only partial availability (A:L).

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

The VobSub subtitle decoder libsub_vob (part of the Amlogic DroidLogic SubTitleService), as shipped on Nexbox A95X (Amlogic S905X) TV boxes, contains an out-of-bounds write vulnerability in vob_fill_pixel() that allows remote attackers to corrupt stack memory by sending a crafted SET_CONTR command with an attacker-controlled alpha value that drives an unbounded array index (change_data) past the end of the fixed four-element PixelDatas array. Attackers can exploit this by sending malicious VobSub data over the unauthenticated tcp/10100 socket or via a malicious .sub file to zero out adjacent stack bytes, resulting in silent stack corruption or process crash.

Threat Intelligence Overview

EPSS Score
0.4%
Top 69% exploitable
Prevalence
Low
cheap niche consumer Android TV box, no enterprise footprint
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC Yes
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

54
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

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